The invention relates to door structures or hatches for roofs, sidewalks and the like, in which the door frame is disposed horizontally or at an angle to the vertical, so that the weight of the door tends to close it. More particularly the invention relates to support members for spring-actuated cylinders which lift the door toward its open position, counter-balancing the weight of the door.
It is common practice to provide doors of this type with one or more lift-cylinders which are mounted near the hinges, each cylinder being loosely received at its lower end in a straight-walled socket member fixed to the door frame, the cylinder being pivotally attached at its upper end to the door. The lift cylinder pushes upward on the door with sufficient force to counter-balance the weight of the door, the base or foot of the cylinder being pressed against the bottom of the socket member with equal force. Due to the fact that the cylinder tilts back and forth about one edge of its base plate each time the door opens and closes, dirt and other foreign matter accumulates under the bottom of the cylinder, so that the cylinder is eventually lifted out of the socket. As this point the cylinder slips laterally off the lip of the socket and is rendered inoperative.
It is a primary object of the present invention to provide a support member which prevents dirt from building up between the bottom of the lift-cylinder and its support member so that the foot of the cylinder cannot become disengaged from that member. Other objects and advantages of the invention will become more apparent from the description hereinafter.